Apparatus for releasing slips



Patented Dec. 30, 1952 AFPARATUS FOR RELEASING SLIPS Thomas Penningtonand Marvin R. Jones, Houston, Tex., assignors, by mesne assignments, toStandard Oil Development Company, Elizabeth, N. J a corporation ofDelaware Application June 11, 1949, Serial No. 98,458

4 Claims.

This invention relates to new and useful improvements in pipe-suspendingdevices and relates particularly to devices for suspending andsupporting tubular conduits, such as casing and tubing, within aborehole.

In the drilling of wells for oil, gas and other iluids, it is thegeneral practice to employ casing or pipe to line the walls of theborehole, with successive inner casing strings of gradually diminishingdiameter being run in as drilling proceeds. Ordinarily, as in landdrilling, the well bore initially traverses a. competent formationhaving suflicient strength to give lateral support to the outermostcasing string and said outer casing is usually cemented within saidformation. Because the competent formation extends substantially to thesurface of the borehole and, therefore, substantially to the upper endof the casing, said casing has sumcient lateral reinforcement throughoutits length to support effectively the weight of the inner casing or pipestrings which are suspended from its upper end thereof through the usualcasing and tubing head arrangements at or near the derrick floor.

However, in the drilling of wells at sea or oflshore, such as on thecontinental shelf in the Gulf of Mexico, off coastal Louisiana andTexas, the drilling operation is carried on over Water of substantia1depth. The borehole initially traverses the formations at the bottom ofthe ocean and this initial formation is largely of a mucky nature and ofinsufiicient mechanical strength to impart the necessary or requiredlateral reinforcement or support to the outer casing. Thus, the firstcompetent underground formation traversed by the borehole is located aconsiderable distance below the derrick floor and upper end of the outercasing so that when the outer casing is cemented or anchored in saidcompetent formation, the point of anchorage of said casing is spacedwell below the extreme upper end of the casing. The upper portion of thecasing which extends through the upper incompetent formation and throughthe water is substantially unsupported laterally and is, in effect, arelative- 1y long slender column which is obviously unstable. tendingthrough the water and air to the derrick floor which. may be as much as50 feet above the level of the sea is subjected to wave action whichimposes considerable lateral loads. Therefore, in marine drilling or inthe drilling of a borehole where said borehole initially traverses anincompetent zone or formation, it is not practical to suspend ortransfer the weight of the inner string of casing or pipe to the outercasing at the upper end of said outer casing through the? usual casingand tubing head arrangements be In addition, this unstable portion ex-'To transfer efiectively the weight of the inner pipe or casing string tothe outer casing and then to the competent formation, it is necessary tolocate the point of suspension of the inner string at an elevationwithin the outer casing where said outer casing has sufficient strengthto transfer the load to the formation. In marine drilling the initialformation below the ocean floor does not always impart the requiredlateral support although it may give some lateral reinforcement to thatportion of the outer casing which extends therethrought. Thus, althoughit is probably preferable to locate the point of suspension of the innerstring substantially opposite the competent formation to which the outercasing is anchored, said point of suspension may, in certain instances,be at an elevation above the competent formation. As the casing hassufficient strength at any selected point to transfer effectively theload to the competent formation, the inner pipe string may be sus--pended within said casing at that point. Since the point or elevation ofsupport or suspension of the inner string is variable, the suspendingmeans or device for said string must be capable of setting at a selectedlevel; also, because the inner string is usually cemented or anchored atits lower end, the suspending device must be capable of being setwithout rotation or manipulation of the inner pipe string and for thisreason, the usual hanger or slip-type supporting devices now in generaluse, are not applicable or satisfactory for supporting the inner string.

It is one object of the present invention to provide an improved devicefor suspending or supporting a pipe string within an outer pipe stringat a desired level or elevation therein, which device is adapted to beactuated ormoved into a set position without the necessity of rotatingor otherwise manipulating the pipe string which it supports.

Another object of the invention is to provide an improved device forsuspending an inner pipe string within an outer pipe string or casingwhich is adapted to operate within the annular space between said pipestrings, said device being actuated by a means controlled from thesurface, whereby the device may be selectively set at any predeterminedlevel or elevation without manipulation or rotation of the inner pipestring.

Still another object of the invention is to provide an improved deviceof the slip-type which will effectively transfer the weight of an innerpipe string to an outer pipe string.

Other objects and advantages of the present invention may be seen fromthe following description taken with the drawing in which Fig. 1 is afront elevation in partial section of a preferred embodiment of theinvention;

the mandrel H, slips l5, and the slip setting rods l9.

Mandrel H is provided with a shoulder i2 for supporting the slips whenin a disengaged position and a tapered section l3 which defines aninwardly sloping surface It adapted to receive slip segments I5 whichmay be four in number or any number which may be desired. The slipsegments l5 are also provided with a sloping surface 55 adapted todovetail with the surface i l, the slip segments i5 being keyed tomandrel H with keys ll to provide horizontal alignment and uniformradial pressure on the outer casing when the slips are in operativeposition. Such key means are shown more clearly in Fig. 1A where it willbe seen that the key means H are arranged between the slip segments ISin slots 23. The slip segments l5 are attached by nuts 13 to slipsetting rods or elongated members l3 arranged in apertures 9 and spacesIE. The rods 19 are connected by cable coupling 23 to a bridlearrangement 33 and to a cable 33 for bringing the slips into operativeposition, employment of the bridle 33 being dispensed with if the cable39 is connected directly to the slip device.

The lower portion of slip segments i5 define a groove 2! into whichthere is fitted a snap ring, or garter spring 22 or other releasablemeans such as a breakable wire, a deformable ring and the like, whichholds the slips into retracted position when setting the sliparrangement on a tubing string down the hole.

The mandrel l I also defines a first slot or passageway 23 in thetapered or sloping section 53 and a second slot or passageway 24 belowslot 23 in shoulder 12 which allows circulation of fluid when the pipeon which the slips are arranged is being run and while cement is beingplaced. These slots define passageways permitting flow of fluid fromabove the device 37 to a point below it and from below the device 31 tothe earths surfaces as desired. The section [3 is preferably segmentedby a plurality of slots 23 to provide a plurality of passageways and toreceive the segmented slip segments 15. The shoulder i2 may similarly besegmented by a plurality of slots 2s. The slots 23 and 24 will alsoallow a plurality of devices embodying slips in accordance with thepresent invention to be arranged in tandem in a tubing string since theslip setting rods IQ of the lower of a plurality of devices as describedmay be run through the slots 23 and 24 as desired.

It will be clear from the description taken with the drawing that themandrel II and the section l3 thereof have a plurality of apertures 9and that the section l3 and the shoulder 22 have a plurality of slots 23and 24, respectively, which provide a passage for flow of fluid past thetubular member of the mandrel ll. Below the slip segments l5 are aplurality of spaces E3 which are defined by the interior surface of theslip segments 25 and an outer surface of the tubular member. Theapertures 9 and the spaces it below the slip segments l5 are inalignment with each other and together provide recesses to re ceive theelongated rod members [9.

Referring now to Fig, 2, numeral 38 designates a bridle arrangedimmediately above mandrel H and which may be constructed of a pipesection slightly larger than the casing string and the mandrel H. Theslip segments IS on mandrel H are attached by nuts l8 to rods l9arranged in a slot 9 of mandrel H and a slot [3 of slip segments IS. Therods H! are connected by coupling 20 to rods 25 which, in turn, areconnected to bridle 38 by a suitable fastening means 26. The bridle 38is also held against mandrel H by a strap 2'! and a shear pin 28 whichis designed to shear under a tension of about 150 to 200 pounds. Cableor wire line 39 is attached to the bridl 38 by a second shear pin 29which will shear under a pull of about 600 to i) pounds. Thus, when atension of about 200 pounds is exerted on the cable 39, pin 28 shearsallowing slip segments 15 to be raised. After the slips are set bysetting down the tubing string the cable 39 may be pulled loose byexerting a greater pull theeron causing pin 29 to rupture.

Referring now to Fig. 3, numeral 30 designates a borehole which has beendrilled below the ocean floor and which traverses an incompetentstructure or sub-surface formation A and then traverses a competentformation or structure B. The borehole 30 is cased in accordance withconventional techniques and is provided with a wellhead 3| in a derrickfloor 32. Derrick floor 32 is arranged in derrick 33 which is providedwith drawworks 34 connected to the wellhead rotary by conventional meansnot shown. Derrick 33 rests on pilings 33a which are driven into theformations below the ocean floor and which preferably traverse formationA and extend into formation B. Cased borehole 30 is cemented incompetent formation B as indicated by C. The incompetent formation A isusually of a mucky nature and although it might provide some lateralsupport for the casing 30 it is not suflicient to reinforce that portionof the casing to the point where vertical loads may be safely imposedthereon. The point of anchorage for the casing is at the cement C in thecompetent formation B, and this point is a considerable distance fromthe extreme upper end of the casing with the result that the entireupper end of the casing above the competent formation does not have anyappreciable lateral support. For this reason, it is not practical tosuspend an inner casing or tubin from the extreme upper end of thecasing 30 as is the usual practice in land drilling. Immediately belowthe wellhead 3! are the conventional blowout preventers 35. An innerpipe or casing string 36 is arranged in the borehole 30 and may besuspended, prior to setting of the slips in accordance with the presentinvention, by elevators and the like. The inner pipe string 36 isprovided with the device in accordance with the present invention whichis illustrated schematically by numeral 31 and is arranged in the innerstring 36. Immediately above the slips 3? is a tripping bridle 38 whichis also shown schematically and is described in detail in Fig. 2. Theslip arrangement 31 encompasses the apparatus described in Fig. 1 and isconnected by the slip setting rods l9 through cable couplings 2.3 to thetripping bridle 38 by strap 21 and pin 28. The bridle 3B is merely athin wall pipe section slightly larger than the inner pipe or casingstring being run and incorporates a receptacle at itsupper end forattaching a special rope socket with a shear pin 29. The upper shear pinreleases with an upward pull of approximately 1200 pounds while thelower pins on the slip arrangement 31 shear at approximately 200 pounds.

Thus, in accordance with the present invention, a device indicatedschematically by 31 in Fig. 3 and shown in detail in Fig. 1 may bearranged in a casing string immediately below the tripping bridle 38 ata point where the cased borehole traverses a formation l3 competent tosupport the weight of the casin and the string of tubing. The cable 39which is run through mat 40 to cable reel 4| then has a tension exertedon it sufficient to shear the pins holding slip arrangement 3! to thebridle 33 and allows the slips to be released for moving into positionin engagement with the borehole 30. The mat 40 may be simply a board orplank having a travel slot in it for the cable 30 or may be a bearing orpulley for the cable 39 at the point it makes a 90 turn down the hole.This mat does not form an essential part of our invention and may bedispensed with. On setting down the inner casing string, the snap ring22 is broken or deformed and the weight of the tubing string istransferred through the slip arrangement 37 to the casing 30 and thenceto earth formation B competent to bear the weight. By exerting additional pressure on the shear pins connecting the cable 39 to thetripping bridle, it is possibl to pull the cable from the annulusdefined by the outer surface of the tubing string and the inner surfaceof the casing string.

The invention will now be described further by the following operationsin which the device of the present invention was set down a borehole andsuccessfully suspended pipe thereon. In this operation, the devicedescribed in Fig. l was installed in place of a coupling on an innercasing or pipe. The device was arranged in the outer casing at adistance substantially below the earths surface and the rotary table. Inrunning the inner casing string, embodying the device of the presentinvention, the slip arrangement was first set at a point less than 100feet below the rotary table. set at this point, the inner casing waswithdrawn and the slip arrangement of the present invention was run thedesired depth below several joints of easing. Wall scratchers were usedat the bottom of the inner casing and this neces sitated raising andlowering the pipe through a space of about six feet approximately fortyor fifty times, employing the elevators. While this operation was takingplace, mud was being conditioned and cement was being placed. Duringthis time, the pump pressure forcing the fluid upwardly in the annuluswas sufficient to shear the equivalent of shear pin 23 and allow thefluid to act as a piston in the annulus against the slips and to causethe slips to be raised by hydraulic pressure and cause them to beengaged with the inner wall of the outer casing on the down stroke. Thedevice of the present inven tion was thus intentionally set and releasedseveral times by hydraulic action of the fluid in the annulus.

After these several operations the cement was then located at thedesired point, as shown at C in Fig. 3, and the slips were set byexerting upward tension on the bridle. Approximately After the slips hadbeen 6v 200,000 pounds of weight wa suspended on the slips at one time.Finally, approximately 145,000 pounds was slacked off on the sliparrangement of th present invention and the cable was pulled free fromthe shear socket by exertion of tension on a cat line attached thereto.

It Will thus be seen from the foregoing runs that the device of thepresent invention may be set by hydraulic action with the fluid actingas a piston in the annulus or that the device may be released tooperative position by exerting an upward tension on a cable or wir linelocated in the annulus defined by the wall of the casing and the outersurface of the inner casing string.

From the foregoing description it will be seen that a simple andeflicient pipe suspending de vice is provided for supporting an innercasing or pipe string within an outer pipe or casing string. The slipsare restrained from moving into operating position by the restraining ortension means until such time as the device is located in the casingstring at the point from which it is desired to suspend the innerstring. When the device has been set at the desired location within theouter casing, operation may be effected without the necessity ofrotating or otherwise manipulating the inner pipe string to which thedevice is attached. As long as the weight is imposed on the slipssegments or members they will be maintained in the expanded or setposition because of the co-action between the surfaces [4 and the innersurfaces of the slips i5. When it becomes necessary to remove the pipesuspending device, an upward movement of the pipe tends to cause surfaceI to move in a direction with respect to the slips 15 which allows slipsto be released from engagement with the outer casing. It is to beemphasized that the device operates entirely within the annulus betweentwo pipe strings even after the slip segments have been moved to andengaged in gripping position. By means of the tension device or springthe pipe suspending device is positively maintained in a non-operativeposition and the slip segments [5 cannot function to move into agripping position on the surface M until an upward force is exerted onthe bridle arrangement 38, as has been described.

It is pointed out that the device is illustrated in the drawings asbeing positioned substantially opposite the competent formation B andthe transfer of the weight is at this point. Although the incompetentformation A may not provide sufficient lateral support to the outercasing to permit the transfer of the weight at the extreme upper end ofthe outer casing, said incompetent formation may impart some lateralsupport and the device 31 may, in some instances, be set at a pointopposite the incompetent formation and probably nearer its lowerportion. In actual practic the device 31 is set at any point in theouter casing where said outer casing has sumcient lateral support topermit efficient transfer of the weight of the inner pipe string"through said outer casing and to the competent forma- It will beapparent to the skilled workman that the foregoing description of theinvention is given by way of illustration and not by Way of limitationand the changes in the size and shape of materials, as well as detailsof the illustrated construction may be mad within the scope of theappended claims without departing from the spirit of the invention.

The nature and objects of the present invention having been completelydescribed and illus r 7 trated, what we wish to claim as new and usefuland to secure by Letters Patent is:

1. A device for suspending pipe and the like which comprises, incombination, a tubular body member adapted to be connected into a pipestring having an outer sloping surface provided with a plurality ofapertures and slots spatially removed from one another, said slotsproviding a passageway for flow of fluid past said tubular member, aplurality of slip segments slidably carried on said sloping surface, aninner surface of said slip segments and an outer surface of said tubularmem ber providing spaces below and in alignment with said apertures, aplurality of elongated members connected to said slip segments slidablyarranged in said apertures and spaces for moving said slip segmentsupwardly on said sloping surface into operative position, frangiblemeans interconnecting said elongated members and said body membernormally holding said elongated members in fixed relationship to saidbody member, means for shearing said frangible means on an upward pullon said elongated members and releasable means embracin said slipsegments arranged for holding same in a retracted position while runningsaid device in a well, said releasable means bein released on shearingsaid frangible means and setting down weight on the pipe string.

2. A device for suspending pipe and the like which comprises, incombination, a tubular body member adapted to be connected into a pipestring having an outer upwardly sloping surface provided with aplurality of apertures and slots spatially removed from one another,said slots providing a passageway for flow of fluid past said tubularmember, a plurality of slip segments slidably carried on said slopingsurface, an inner surface of said slip segments and an outer surface ofsaid tubular member providing spaces below and in alignment with saidapertures, a plurality of elongated rod members connected to said slipseg ments slidably arranged in said apertures and spaces for moving saidslip segments upwardly on said sloping surface into operative position,frangible means interconnecting said rod members and said body membernormally holding said rod members in fixed relationship to said bodymember, means for shearing said fran ible means on an upward pull onsaid rod members, releasable means embracing said slip segments arrangedfor holding same in a retracted position while running said device in awell, said releasable means being released on shearing said frangiblemeans and setting down weight on the pipe string, and means arrangedabove said body member and frangible means connected to said frangiblemeans for exerting an upward force on said rod members.

3. A device for suspending ipe and the like which comprises, incombination, a tubular body member adapted to be connected into a pipestring having anouter upwardly sloping surface extending a major lengthof said member and a shoulder adjacent a lower end of said member, saidsurface and said shoulder being provided with a plurality of slotsproviding passageways for flow of fluid past said tubular member, saidsurface being further provided with a plurality of apertures spatiallyremoved from the slot in said surface, a plurality of slip segmentsslidably carried on said sloping surface, an inner surface of said slipsegments and an outer surface of said tubular member providing spacesbelow and in alignment with said apertures, a plurality of elongated rodmembers connected to said slip segments slidably arranged in saidapertures and spaces for moving said slip segments upwardly on saidsloping surface into operative position, frangible means interconnectingsaid rod members and said body member normally holding said rod membersin fixed relationship to said body member, means for shearing saidfrangible means on an upward pull on said rod members, releasable meansembracing said slip segments arranged for holding same in a retractedposition while runnin said device in a well, said releasable means beingreleased on shearing said frangible means and setting down weight on thepipe string, and means arranged above said body member and shearingmeans connected to said shearing means for exerting an upward force onsaid rod members.

4. A device for suspending pipe and the like in a borehole from a pointintermediate a top and bottom thereof which comprises, in combination, atubular body member adapted to be connected into a pipe string having anouter upwardly sloping surface extending a major length of said membeerand a shoulder adjacent a lower end of said member, said surface andsaid shoulder being provided with a plurality of slots providingpassageways for flow of fluid past said tubular member, said surfacebeing further provided with' a plurality of apertures spatially removedfrom the slots in said surface, a plurality of slip segments slidablycarried on said sloping surface, key means on said tubular body memberarranged in the slots in said sloping surface in engaging relationshipwith said slip segments, an inner surface of said slip segments and anouter surface of said tubular member providing spaces below and inalignment with said apertures, a plurality of elongated rod membersconnected to said slip segments slidably arranged in said apertures andspaces for moving said slip segments upwardly on said sloping surfaceinto operative positions, releasable means embracing said slip segmentsarranged for holding same in a retracted position while running saiddevice in the borehole, said releasable means being released on settingdown weight on the pipe string, a bridle member arranged above saidtubular body member and connected thereto by a first frangible means,means connecting said elongated rod members to said bridle member, and asecond frangible means connecting said bridle to a cable extending tothe top of the borehole, said first and second frangible means beingadapted to be sheared sequentially on first and second upward pulls onsaid cable, said first pull releasing said bridle from the body memberfor moving said slip segments upwardly on said sloping surface onsetting down weight on the pipe string and said second pull releasingsaid cable from said bridle.

THOMAS PENNINGTON. MARVIN R. JONES.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

